In the tape recorder, a tape is engaged in between the capstan and the pinch roller, moved by the rotation of the capstan, and wound on a take-up reel. In this movement, if the rotation of the take-up reel is disturbed for any reason, the tape becomes loose so that it might be rolled on the capstan or the pinch roller.
Also, if the tape becomes loose. The tape cassette during non-use, the same problem may arise at the time of starting a take-up operation.
When the tape is rolled on the capstan or the pinch roller, the tape breaks down or the tape cassette cannot be drawn out. Therefore, in a conventional tape recorder several means have been utilized to solve these problems. First, as a mechanical means, it is possible to prevent the tape from being rolled on the capstan or the pinch roller by making an opening on the pinch roller arm which supports the pinch roller to be rotated, and discharging the relaxed tape through the opening. Second, as a electrical means, it is possible to prevent the tape from being rolled on the capstan or the pinch roller by mounting a photosensor in the vicinity of the capstan, and producing an electric signal in the photosensor to detect a relaxed tape and stop the drive motor, or by electrically detecting a change in the rotation speed of the reel from a given range of rotation speeds so as to stop the drive motor.
However, there have been some problem in both means. In the mechanical means, it is difficult to prevent the tape from being rolled when the relaxed tape is not exactly discharged through the opening. In the electrical means, the device is complicated and the cost is high because it requires photosensors, electric circuits, and so forth.